The progression of myopia from its onset at age 8-12 to adulthood and the influence of heredity and external factors on myopic progression. A 23-year follow-up study.

PURPOSE To examine myopic progression and factors connected with myopic progression. METHODS Myopic schoolchildren, with no previous spectacles, 119 boys and 121 girls, were recruited during 1983-1984 to a randomized 3-year clinical trial of bifocal treatment of myopia with a subsequent 20-year follow-up. Participants' mean age at Baseline was 10.9, ranging from 8.7 to 12.8 years. An ophthalmological examination was carried out annually for 3 years and twice thereafter at ca. 10-year intervals. Additional refraction values were received from prescriptions issued by different ophthalmologists and opticians. Altogether, 1915 refraction values were available. Reading distance and accommodation were measured at each control visit. Data on parents' myopia, daily time spent on reading and close work, outdoor activities and watching television were gathered with a structured questionnaire. RESULTS Using bifocals (+1.75 add) or reading without glasses or accommodation stimulus during the 3-year period in childhood did not correlate with adulthood refraction. Short reading distance in childhood predicted higher adulthood myopia among females. The factors predicting faster myopic progression were parents' myopia and less time spent on sports and outdoor activities at childhood. Time spent on reading and close work in childhood was related to myopic progression during the first 3 years but did not predict adulthood myopia. Myopia throughout follow-up was higher among those who watched television <3 hr daily than those who spent more time watching television. Mean myopic progression 8 years after age 20-24 was -0.45 D ± 0.71 (SD), and in 45% of cases, progression was ≥0.5 D. CONCLUSIONS In nearly half of the cases, myopia beginning at school continued to progress into adulthood. Higher adulthood myopia was mainly related to parents' myopia and less time spent on sports and outdoor activities in childhood.